Distributed Control

Profibus PA enhancements win NAMUR approval

Source: ControlGlobal.com

By Andrew Bond, Industrial Automation Insider

Jan 23, 2009

Innovations to be included in the forthcoming new version of the process automation oriented fieldbus protocol Profibus PA, due for release in the first quarter of 2009, have been given the seal of approval by the fieldbus working group of NAMUR, the international association of process automation user companies based in Germany. Representatives of NAMUR Working Group 2.6 particularly welcomed the field device integration measures introduced in the new profile. These are specifically aimed at simplifying life-cycle management and are seen as taking the lead in satisfying customer requirements in the area of digital fieldbus communication.

Simplified field device integration is addressed in three ways: by providing support for device replacement, even after changeover to a new generation; by simplifying the handling of device integration through driver files for Profibus GSD (Generic Station Description), EDD (Electronic Device Description) and DTM (Device Type Manager); and by optimized assignment of driver files to field device versions over the entire life cycle of the field devices.

Since 2005 Profibus PA has supported the representation of status and diagnostic information in accordance with the categories defined in NAMUR Recommendation 107 “Self-Monitoring and Diagnosis of Field Devices.” However, this will now become mandatory for all PA field devices, thereby implementing a single uniform representation of status and diagnostic information across all devices irrespective of vendor. Loading and readout times for device parameter sets will also be shorter under the new profile, allowing faster commissioning and device replacement and speeding up diagnostic and maintenance work.

Other measures that received the blessing of the NAMUR working group included the arrangements for checking the compatibility rules during Profibus certification, the user guidelines developed for working with GSD, EDD and DTM driver files during the equipment life cycle and the guidelines for device replacement. The working group saw the new profile as having the potential significantly to reduce fieldbus related engineering and operating costs and contributing to the minimization of life-cycle costs.

Ten years after the first introduction of ProfiSafe, the total number of installed nodes is expected to comfortably exceed 700,000 by the end of 2008, an increase of some 80% on the year. ProfiSafe introduced the concept of implementing safety functions via Profibus and ProfiNet without the need for separate “second relay level” hard wiring. It is based on the so-called black-channel principle which allows secure transmission from end point to end point via proprietary backplane buses as well as via Profibus and ProfiNet. Additionally it enables the use of integrated safety functions in drives. In the intervening years, a number of quality measures have been implemented, including a certification program for field devices and safety controllers, a development kit with a pre-certified ProfiSafe driver and training sessions conducted with TÜV leading to ‘ProfiSafe Certified Designer’ status. Most recently PI has introduced certification for safety-related hosts (F-Hosts) comprising ProfiSafe host software running in a Profibus or ProfiNet certificated controller.